1. Field of the Invention
The present invention relates to a method and apparatus for rendering an image signal using a multicolored image signal rendering apparatus, and more particularly, a method and apparatus for rendering an image signal by adding a fourth color component, to an image signal composed of three colors (for example, RGB).
2. Description of the Related Art
In a conventional apparatus for rendering an image signal, a pixel is composed of sub-pixels having three different colors, for example, red (R), green (G), and blue (B). FIG. 1 shows an example of a filter arrangement of an RGB-striped structure.
FIG. 2 shows an example of an RGBW filter structure of a conventional RGBW type apparatus for rendering an image signal in which luminance is improved by adding a fourth color sub-pixel (for example, white) to sub-pixels representing RGB colors. In methods for rendering a four-channel image signal by which white or a certain primary color is added to three RGB channels as shown in FIG. 2, when the added primary color is white, an output light of the primary color can be increased, and when the added primary color is a primary color excluding RGB colors, a renderable color area can be enlarged.
In the case of the RGBW filter shown in FIG. 2, if the same pixel area is used simultaneously, due to a high transmittance of a white filter, the output light of the pixel can be increased. However, since one white filter is added to each pixel, the sizes of RGB filters become smaller compared to a pixel in which only three RGB colors are used as shown in FIG. 1. As such, the output light of RGB primary colors becomes rather reduced compared to the pixel in which only three RGB sub-pixels are used. Also, since driver integrated circuits (ICs) for driving the white filter are needed, manufacturing costs of these filters increase.
FIG. 3 shows another example of an RGBW filter structure of a conventional RGBW type apparatus for rendering an image signal in which luminance is improved by adding a fourth color sub-pixel (for example, white) to sub-pixels of GB colors. Here, although pixel is composed of 2×2 sub-pixels, the same problems as in the RGBW filters shown in FIG. 2 occur.
FIG. 4 shows still another example of an RGBW filter structure of a conventional RGBW type apparatus for rendering an image signal in which luminance is improved by adding a fourth color sub-pixel (for example, white) to sub-pixels of RGB colors. There is only one difference from the RGBW filter structure shown in FIG. 2, i.e., the sizes of blue and white filters are small and the sizes of red and green filters are the same as the sizes of sub-pixels of R and G colors at a pixel in which only three RGB colors are used. Thus, with an output light increase caused by the white filter, an output light decrease of primary colors such as red and green can be prevented. However, since the driver ICs for driving the white filter are additionally required, the manufacturing costs in this case increase as well.